The role of ionization electrons in direct neutralino detection

In this Letter we estimate the event rates of neutralino-nucleus scattering leading to electron emission by the atomic ionization. We find that the branching ratio for detecting electrons vis-a-vis the traditional neutralino-nucleus elastic scattering sensitively depends on the threshold energy. In the case of a light target and a neutralino mass of 100 GeV we estimate it to be around 10 percent assuming a reasonable threshold energy of 250 eV. (C) 2004 Published by Elsevier B.V.